Sexually Transmitted Disease Surveillance 1996

Division of STD Prevention September 1997

U.S. Department of Health and Human Services 
Public Health Service 
Centers for Disease Control and Prevention  
National Center for HIV, STD, and TB Prevention 
Division of STD Prevention 
Atlanta, Georgia 30333

Copyright Information 

All material contained in this report is in the public domain and may be
used and reprinted without special permission; citation to source, however,
is appreciated.

Suggested Citation

Division of STD Prevention. Sexually Transmitted Disease Surveillance,
1996. U.S. Department of Health and Human Services, Public Health Service.
Atlanta: Centers for Disease Control and Prevention, September 1997.

Copies can be obtained from the Office of Communications, National Center
for HIV, STD, and TB Prevention, Centers for Disease Control and
Prevention, 1600 Clifton Road, Mailstop E-06, Atlanta, Georgia 30333.

The reports for 1993 through 1996 are available electronically on CDC
WONDER. For information about registering for CDC WONDER, please contact
CDC's Epidemiology Program Office at (888) 496-8347. These reports are also
available from the Internet via the CDC home page address
http://wonder.cdc.gov/wonder/data/Reports.html. 


Sources and Limitations of Data 

CDC Surveillance Data

Much of the information in this document was based on cases of sexually
transmitted diseases (STDs) reported to the Division of STD Prevention
(DSTDP), Centers for Disease Control and Prevention (CDC), by the STD
control programs and health departments in the 50 states, the District of
Columbia, selected cities, U.S. dependencies and possessions, and
independent nations in free association with the United States. Included
among the dependencies, possessions, and independent nations are Guam,
Puerto Rico, and the Virgin Islands. These entities are identified as
"outlying areas of the U.S." in selected tables and figures. At present,
STD data are submitted to CDC on a variety of hardcopy summary reports
(monthly, quarterly, and annually) and electronically either in summary or
individual case-listed format. DSTDP is currently working on converting
from hardcopy reporting of summary data to electronic submission of
line-listed (i.e., case-specific) data. The data used in this report are
predominantly based on the summary hardcopy reports. Monthly reports
included summary data for syphilis by county and state. Quarterly reports
included summary data for syphilis, gonorrhea, chlamydia, and other STDs by
gender and source of report (STD clinic or non-STD clinic) for the 50
states, 64 large cities (most with a population over 200,000 in 1980), and
outlying areas of the United States. Annual reports included summary data
for syphilis, gonorrhea, and chlamydia by age, race, and gender for the 50
states and six large cities. In addition, data on antimicrobial
susceptibility in Neisseria gonorrhoeae were collected through the
Gonococcal Isolate Surveillance Project (GISP), a sentinel system of 25 STD
clinics and five laboratories located throughout the United States.
Provisional data on syphilis, gonorrhea, and chlamydia reported to CDC
weekly by states for inclusion in the Morbidity and Mortality Weekly Report
were not included in this document.

Areas differ in their ability to resolve differences in total cases derived
from hardcopy monthly, quarterly, and annual reports (as well as
electronically submitted case-listed data). Thus, depending on the database
used, there may be discrepancies in total cases in the tables and figures.
In most instances, these discrepancies are less than 5% of total reported
cases and have minimal impact on national total cases and rates. However,
for a specific area, the discrepancies may be larger.

Reports and corrections sent to CDC through June 13, 1997 have been
included. Those received after this date will appear in subsequent issues.
The data in the tables and figures in this document supersede those in all
earlier publications.

Population Denominators and Rate Calculations

Crude incidence rates (new cases/population) were calculated on an annual
basis per 100,000 population. For the United States, rates were calculated
using Bureau of the Census population estimates for 1981 through 1989
(Bureau of the Census; United States Population Estimates by Age, Sex and
Race: 1980-1989 {Series P-25, No. 1045}; Washington: US Government Printing
Office, 1990; and United States Population Estimates by Age, Sex and Race:
1989 {Series P-25, No. 1057}; Washington: US Government Printing Office,
1990). Rates for states and counties were calculated using published
intercensal estimates based on Bureau of the Census population estimates
for 1980-1989 (Irwin R; 1980-1989 Intercensal Population Estimates by Race,
Sex, and Age; Alexandria, {VA}: Demo-Detail, 1992; machine-readable data
file). Rates for 1990 were calculated using population data from the 1990
census (Census of Population and Housing, 1990: Summary Tape File 1 (All
States) {machine-readable file}; Washington: Bureau of the Census, 1991),
which included information on area (county, state), age (5-year age
groups), race (White, Black, Asian/Pacific Islander, American Indian/Alaska
Native) and ethnicity (Hispanic). Rates for 1991-1994 were updated from
previous issues of this report using postcensal population estimates based
on the Bureau of the Census data (U.S. Bureau of the Census; 1991-1994
Estimates of the Population of Counties by Age, Sex and Race/Hispanic
Origin: 1990 to 1994; machine-readable data file). Rates for 1995 and 1996
use extrapolated population estimates for 1995. 

Many cities do not have a separate health jurisdiction that collects and
reports cases of STDs. For these cities, case numbers and crude incidence
rates are equal to those of the county or counties in which the city is
located. For the remaining cities, incidence rates were calculated by using
population estimates based on the Bureau of the Census (Irwin R, see above)
and a marketing survey (Market Statistics, Inc; Sales and Marketing
Management; New York: Bill Communications, Inc, August 1989).

1980-1988 population estimates for areas outside the United States were
obtained from the Bureau of the Census (Bureau of the Census; population
estimates for Puerto Rico and the outlying areas: 1980 to 1988; Current
Population Reports {Series P-25, No. 1049}; Washington: US Government
Printing Office, 1989). After 1988, population estimates for outlying areas
were obtained directly from the health departments in these areas. For
Puerto Rico, population estimates for 1996 were based on 1995 population
estimates. For the Virgin Islands, rates for 1993-1996 were based on 1992
population estimates, and for Guam, rates for 1991-1996 were based on 1990
population estimates because more current estimates were unavailable.

The percentage of cases for which race/ethnicity and age were unknown or
unspecified differed considerably, depending on year and area. In 1983 and
1984, up to 25% of total U.S. cases were in this category. In these years,
states were excluded from analysis if race/ethnicity and age were not
reported for the majority of cases. Otherwise, if race/ethnicity or age was
unknown or unspecified, cases were distributed according to the
distribution of cases for which these data were available. In this edition,
1981 through 1996 age- and race-specific rates (for chlamydia (1996 only),
gonorrhea, and syphilis in the National Profile, Special Focus Profiles and
Detailed Tables) are calculated from estimates based on this
redistribution. 

Rates of congenital syphilis for 1989-1996 were calculated using live
births from the National Center for Health Statistics (NCHS) (Vital
Statistics: Natality Tapes 1989-1994 or Vital Statistics Reports, United
States 1997, Vol. 45 No.6--Natality). Race-specific rates for 1995-1996
were calculated using live births for 1994. Rates before 1989 were
calculated using published live birth data (NCHS; Vital Statistics Report,
United States, 1988 {Vol.1--Natality}).

Case Definitions and Reporting Practices

Although most areas generally adhere to the case definitions for STDs found
in Case Definitions for Public Health Surveillance (MMWR 1990;39(RR-13):
1-43), there are significant differences between individual areas in case
definitions as well as in the policies and systems for collecting
surveillance data. Thus, comparisons of case numbers and rates between
areas should be interpreted with caution. However, since case definitions
and surveillance activities within a given area remain relatively stable,
trends should be minimally affected. In many areas, reporting from publicly
supported institutions (e.g., STD clinics) was more complete than from
other sources (e.g., private practitioners). Thus, the trends may not be
representative of all segments of the population. Military cases are not
reported as a separate category.

Reporting of Congenital Syphilis Cases

In 1989, a new surveillance case definition for congenital syphilis was
introduced. The new case definition has greater sensitivity than the former
definition. In addition, many areas greatly enhanced active case finding
for congenital syphilis during this time. For these reasons, the number of
reported cases increased dramatically during 1989-1991. As is true of any
change, a period of transition during which trends cannot be clearly
interpreted has resulted; however, all reporting areas had implemented the
new case definition for reporting all cases of congenital syphilis after
January 1, 1992. Therefore, the reliability of trends is expected to have
stabilized after this date.

In addition to changing the case definition, CDC introduced a new data
collection form (CDC 73.126) in 1990. Beginning with 1995, the data
collected on this form are used for reporting congenital syphilis reported
cases and associated rates. This form collects individual case information
which allows more thorough analysis of cases. For the purposes of these
analyses if either race or ethnicity question was answered, the case was
included. For example, if "White" race was marked, but ethnicity was left
blank, the individual was counted as "non-Hispanic White".

Reporting of Gonorrhea Cases

In 1994, Georgia reported gonorrhea cases to CDC for only part of a year.
Therefore, Georgia cases and population were excluded from gonorrhea
figures and tables for 1994. The city of Atlanta was also excluded from
city figures and tables for 1994.

Reporting of Chlamydia Cases

Effective February 1996, Alaska initiated mandatory reporting of Chlamydia.
In 1996, New York was the only state that did not yet have laws or policies
for uniform reporting of Chlamydia trachomatis cases. Chlamydia cases for
New York were exclusively based on cases reported by New York City (i.e.,
no cases were reported outside of New York City). When calculating U.S.
total rates, the population denominators were adjusted to include only the
New York City population. Trends in many areas were more representative of
increases in reporting of cases rather than actual trends in disease. Cases
and rates of chlamydia reported in gender-specific tables are
underestimated due to some reported cases with unknown gender. Despite
problems with under-reporting, it is important to publish the data to
emphasize the large numbers of cases of chlamydia being detected in the
United States. As areas develop chlamydia prevention and control programs,
including improved surveillance systems to monitor trends, the data should
improve and become more representative of true trends in disease.

Chlamydia test positivity was calculated by dividing the number of women
testing positive for chlamydia (numerator) by the total number of women
tested for chlamydia (denominator) and was expressed as a percentage. While
not common, the denominator may contain multiple tests from the same
individual if that person was tested more than once during a year. Various
chlamydia test methods were used and no adjustments of test positivity were
made based on test type. Chlamydia testing data for region- and
state-specific figures were published with permission from the HHS Regional
Infertility Prevention Programs, selected state STD prevention programs,
and the Job Corps, U.S. Department of Labor. Health and Human Services
(HHS) regions are as follows: Region I=Connecticut, Maine, Massachusetts,
New Hampshire, Rhode Island, and Vermont; Region II=New Jersey, New York,
Puerto Rico, and U.S. Virgin Islands; Region III=Delaware, District of
Columbia, Maryland, Pennsylvania, Virginia, and West Virginia; Region
IV=Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South
Carolina, and Tennessee; Region V=Illinois, Indiana, Michigan, Minnesota,
Ohio, and Wisconsin; Region VI=Arkansas, Louisiana, New Mexico, Oklahoma,
and Texas; Region VII=Iowa, Kansas, Missouri, and Nebraska; Region
VIII=Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming;
Region IX=Arizona, California, Guam, Hawaii, and Nevada; and Region
X=Alaska, Idaho, Oregon, and Washington.

Other Data Sources

The information on the number of initial visits to private practitioners'
offices for sexually transmitted diseases was based on analysis of data
from the National Disease and Therapeutic Index (NDTI) (machine-readable
files or summary statistics for years 1966-1996). For more information on
this database, contact IMS America, Ltd., 660 West Germantown Pike,
Plymouth Meeting, PA 19462; Telephone: (610) 834-5000.

The information on patients hospitalized for pelvic inflammatory disease or
ectopic pregnancy was based on analysis of data from the National Hospital
Discharge Survey (machine-readable files for years 1980-1994), an ongoing
nationwide sample survey of short-stay hospitals in the United States,
conducted by the National Center for Health Statistics. For more
information, see Graves EJ; 1988 Summary: National Hospital Discharge
Survey; Advance data No. 185; Hyattsville (MD): National Center for Health
Statistics, 1990. The National Hospital Ambulatory Medical Care Survey
(NHAMCS) (machine-readable file for 1994) was used to obtain estimates of
the number of emergency room visits for pelvic inflammatory disease among
women ages 15 to 44. The estimates generated using these data sources (NHDS
and NHAMCS) are based on statistical surveys and therefore have sampling
variability associated with the estimates.

Healthy People Year 2000 Revisions

In 1995, the Healthy People year 2000 objectives were revised (1). The year
2000 objectives for the diseases in this report were revised as follows:
primary and secondary syphilis -- 10 per 100,000 population to 4;
congenital syphilis -- 50 per 100,000 livebirths to 40; and gonorrhea --
225 per 100,000 population to 100.

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(1) Department of Health and Human Services. Healthy People 2000: Midcourse
    Review and 1995 Revisions. U.S. Department of Health and Human
    Services, Public Health Service. U.S. Government Printing Office,
    Washington, D.C., 1995.

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